1. Field of the Invention
The invention relates to a process for the production of a pectin preparation, and particularly of fruit pectin, e.g., apple pectin, which is suitable for the production of jellies with a particularly low solids content.
2. Description of the Prior Art
Highly esterified pectins form jelly, in which the gel formation is based on a dehydration and electrical neutralization of colloidally dispersed and hydrated pectin agglomerates. In addition, sugar or a sugar substitute material must be present as a dehydration agent at a concentration of almost 65%, and the required pH value must be maintained within a narrow tolerance range. The individual pectin molecules are, at the same time, linked by hydrogen bonds, which are formed with the sugar.
Partially esterified pectins, i.e., pectins with a degree of esterification less than 50%, have gelling or thickening properties which are similar to those of agar or gelatin. Partially esterified pectins are used in the food industry, for example, for the production of low solids jellies, milk puddings and sugar-free jellies.
The gelling property of partially esterified pectins depends upon the amount of pectin, the solid content, the pH value and the buffer salt content and on the amount of calcium ion present. Moreover, the calcium ion concentration plays a significant role in which the optimum amount of calcium ion changes as a function of the degree of esterification. The optimum calcium content, expressed in mg Ca/g of pectin, which forms a solid gel, is a defined quantity for a particular pectin. If this calcium concentration is exceeded, a brittle gel results with a strong tendency towards syneresis. At the same time, the dependence on the pH value and the solids content plays only a subordinate role. For the technological application of these pectins, the following factors are, however, unfavorable:
1. THE LOWER THE DEGREE OF ESTERIFICATION OF A PECTIN, THE LESS IS ITS SOLUBILITY IN WATER;
2. FOR MAINTAINING AN OPTIMUM CALCIUM ION CONCENTRATION, AN ADDITION OF CALCIUM IS USUALLY NECESSARY. This addition depends on the water used and on the fruit.